Pet food products are generally divided into three categories: dry, semi-moist, and canned. Although there are no industry standards, dry pet foods typically have a moisture content of less than 15% and generally have a dry, crunchy texture. Semi-moist foods typically have a moisture content in the range of 15 to 50%. Canned foods generally have a moisture content above 50%, and often around 70%. The development and production of various pet food products in these three categories is well known in the art. Food products such as cat and dog food have been known for years, and those skilled in the art are aware of multiple formulations and processes for preparing such products. There remain, however, continuing problems within the art.
Over the years, various techniques have been utilized in attempts to improve the palatability of pet foods. U.S. Pat. No. 3,857,968 discloses a process for improving the palatability of animal foods, such as dog foods, through the enzymatic treatment of a mixture of fat and protein. The patent does not identify the reason for the improvement in palatability. It is disclosed, however, that the reaction produces a complex array of reaction products, which may be responsible for the improvement.
Amino acids are thought to have widely varying aromas and flavors depending upon their type and concentration. There is nothing known in the art to indicate the inherent attractiveness of certain amino acids to dogs. Thus, while U.S. Pat. No. 4,267,195 discloses that L-proline, L-cysteine, L-histidine, and L-lysine are taste active in dogs, there is an apparent need to balance the level of amino acids depending upon the particular composition of the dog food. A more general reference to the flavorful effect of amino acids is made in U.S. Pat. No. 3,653,908, which discloses an intermediate-moisture animal food especially formulated for cats.
U.S. Pat. No. 4,282,254 discloses other amino acids to increase the palatability of dog food.
U.S. Pat. No. 3,745,023 teaches that a specially treated fat preparation may improve palatability when applied to pet foods. A high concentration of free fatty acids may promote palatability.
It is also thought that various sugars may improve the palatability of dog foods. For example, U.S. Pat. No. 3,617,300 to Borochoff et al. indicates that dextrose may improve the palatability of dog foods. According to the disclosed process, some of the starch content of a solid dog food is enzymatically converted to glucose directly in the dog food by α-amylase and amyloglucosidase. This patent teaches that the combination of these two enzymes permits the reaction to occur without adversely affecting the solid character of the dog food.
U.S. Pat. No. 4,393,085 teaches that the palatability of dog food may be improved when at least a potion of the farinaceous ingredients are subjected an amylase enzyme digestion, and protease enzyme digestion and proteinaccous ingredients and a protease are added to the enzymatically modified farinaceous material to form a reaction slurry mixture. The resulting combined reaction slurry mixture can be incorporated into the dog food by coating it on the surface or admixing it with the other dog food ingredients. α-Amylase is also used in the production of maltodextrins as disclosed in U.S. Pat. No. 3,849,194.
While it is recognized that many features contribute to the taste of pet food, it is also recognized that the texture or relative softness of a pet food is also important. Softness is a particular problem with dry dog foods because dry, hard pet foods are sometimes not well accepted by the animal. U.S. Pat. No. 4,540,585 discloses that α-amylase can be added to semi-moist pet foods to improve the softness. To Applicant's knowledge, it is unknown to add α-amylase to a dry pet food to improve palatability and make the food softer. Humectants have also been tried in an effort to maintain a soft texture in pet foods, i.e. U.S. Pat. No. 3,202,514.